MIT hopes to cut the VR cord with ‘millimeter wave’ wireless headsets

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Every VR demo on a PC I’ve seen begins with someone apologizing for the tether. At least with hosted demos, there is someone to manage the cord. Once you set up your own system, you’re left to trip over it shortly after you immerse yourself in your favorite VR game. Currently, the only way around having a tether is by using an expensive, special-purpose, backpack VR PC. Those aren’t all that much fun, either. Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) aim to fix the problem by letting you cut the cord. By harnessing millimeter waves (mmWaves) along with a programmable reflector called MoVR, they expect to be able to provide enough two-way bandwidth to enable high-quality VR experiences without wires.

High-performance VR is hampered by the need for a tether

High-end VR headsets like the Vive and Oculus Rift feature two HD or better displays. That means they need to be fed data at nearly 6Gbps, with very-low latency. This has to happen while the user is moving around as they play a game or go through a VR experience. Today, that is almost always achieved by using a high-quality HDMI cable from the PC to the headset. In commercial settings it may be partially suspended from above, to stay off the floor. But for most consumers it’s snaked across the floor, where it can easily be run over by a chair, tripped on, or tangled up.

Improving on the promise of mmWaves

Millimeter waves are well understood as a way to transmit large amounts of data quickly over small distances. However, because they use very-high frequencies — from 30 to 300 GHz — they require line of sight between the transmitter and receiver. In the case of VR, that’s a problem because users are constantly turning their head, moving around, and gesturing. Any of those can quickly drop the signal. Unlike other kinds of data transmission, VR experiences can’t tolerate a momentary loss of signal, so mmWaves have been a non-starter for VR applications — until now.

The team at MIT has improved on typical mmWave system designs by adding a programmable signal reflector it calls MoVR (think repeater) that can quickly retarget, amplify, and retransmit a mmWave signal. The source AP (Access Point) and the MoVR use sophisticated real time signal processing to determine the correct angle of reflection for the programmable “mirror”, so that it will always be sending the signal directly to the headset-based receiver. Based on multiple simulations, having the signal come from both the AP and the MoVR is enough to insure that there is connectivity to the receiver under most conditions (short of the user completely blocking the receiver with their hand, for example). For more information, the authors have put their research paper online.

Other approaches to cutting the cord

In addition to using a VR backpack, there are other cordless solutions. Most common are smartphone-based devices, like Google Cardboard, Samsung Gear VR, and Google’s Daydream. However, by definition, these are much less powerful than those that harness a mainstream CPU and GPU. Microsoft HoloLens, and a few others, have taken the approach of stuffing an entire computer into their headsets. That’s an appealing option, but for now an expensive one that is still in the testing stages with developers.

More recently, HTC just announced a $220 wireless accessory for the Vive. By mounting it on top of the user’s head, it avoids some of the worst of the interference problems. But HTC and developer TPCAST have said little about the technology. If it is a traditional HDMI repeater, then it won’t solve the problem of gesturing, or even leaning over away from the transmitter. I look forward to MIT’s MoVR changing that.

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KIMS

I don’t know in-depth details of WiFi, so these are just my thoughts coming from a naive starting point!

If you based yourself on WiFi, but with custom ‘receiver’ and ‘transmitter’, locked down so it becomes a 1:1 node private network and you do away with a lot of the router and protocol overheads, would that be enough to get latency down low enough?
Is not a lot of the delays in typical Wi-Fi networks due to switch processing and supporting ‘everything’ and multiple users at the same time etc?

So if you set it up from a hardware and firmware point of view to only ever be a 1 to 1 node system, you can trim out most all routing logic etc. And since you control both the sender and the receiver, you don’t need to negotiate standards etc., and you can make the sort of design choices (both hardware and firmware) that you cannot do if you go for wide product and standard support?

You could still be in trouble if you have a lot of network noise nearby, but for such short ranges (20′ max?) you should be able to get the speed and coverage you need? No? Comments?

Crunchy005

Yes, direct wifi removes a lot of overhead and can achieve much faster/consistent response times with wifi. VR needs a frame refresh every ~11ms to hit 90 FPS so the wifi transmission needs to happen much faster than that since the computer already can take 4-11+(depending on hardware) MS just to process everything, hence the 30-300GHz range we are working with. These frequencies are used so we get a lot of bandwidth to send a 1200p video signal to the headset as well as gathering data(not to sure what kind or extent of data the headsets send/receive). As for network noise I don’t know of many things if any that run at these frequencies and would be in your house so that doesn’t seem like it would be an issue.

ZEN

If they Split up the Data for each eye on to different frequencies and used multiple attennas you’d reduce the bandwidth required.

I still think Ligo technology is the way forward for VR, especially if the standard still has a lot of room to be improved.

Crunchy005

You aren’t reducing bandwidth required, it’s the same data. You are just splitting up the signals. Also would that not have a risk of becoming out of sync every so often? Talk about nausea one eye falls behind while the other moves perfectly, lol. Really why don’t they just put the stupid reciever on a long cable that can be mounted on the ceiling over the play area, then the transmitter is on the headset and nothing should get in the way. Not the most convenient but it would work, I mean you already have to have multiple towers for room scale.

Justanotherokie

Sounds good, lets move some radiation around to the frontal lobe so the temporal lobe doesn’t have to take all the radiation.